The present invention relates to a hydraulic regulating device which is used to regulate speed-dependent pressure supplied to the control means of an automatic automobile transmission. Specifically, this type of regulating device, which controls the speed-dependent pressure by means of two pressure release valves loaded by flyweights, has been improved by the addition of a third flyweight mounted to interact with one of the other flyweights to provide improved control of hydraulic fluid pressure variation with speed.
The improvement of the present invention is directed towards hydraulic regulating devices of the type that is disclosed, for example, in German letters of disclosure No. 1,960,683, publicly laid open June 25, 1970. These regulating devices include a primary shaft which has a duct which provides a supply of hydraulic fluid from a pressurized hydraulic fluid source to a control mechanism for an automatic automobile transmission. In order to meet the varying fluid demands of the control mechanism at varying vehicle speeds, the duct has two pressure release valves which control fluid pressure by permitting hydraulic fluid to flow out through two pressure control openings. The pressure release valves are loaded by flyweights mounted on the regulating device and responding to rotation of the primary shaft. The centers of gravity of the flyweights are located laterally from the shaft axis so that upon rotation of the regulator shaft, centrifugal force causes the flyweights, which act directly on the pressure release valves, to urge the release valves toward the closing position.
When the performance of this type of regulator device is characterized by a graph plotting regulated fluid pressure against vehicle speed, a curve consisting of two parabolic arcs which intersect at one point results.
It has been found that this characteristic hydraulic fluid pressure curve reveals a regulator performance which is not, at all times, sufficient to meet the demands made for transmission control. The demands of the automatic transmission control are best met when the characteristic curve produced by the regulator is relatively flat. Furthermore, regulators of this type, known to date, require flyweights which are relatively complex in shape and which must be fabricated with a high degree of precision in order to ensure the most constant characteristic possible.
It is therefore an object of the present invention to provide a regulator device to regulate the speed-dependent pressure for the control mechanism of an automatic automobile transmission which achieves a characteristic curve flatter than the characteristic curves of other pressure regulators of this kind.
It is a further object of the present invention to provide such an optimally performing regulating device having flyweights which have shapes that are simply and economically attainable and which may be more conveniently arranged on the device.